Tuesday, November 24, 2015

Science | The war against malaria has a new ally: a controversial technology for spreading genes throughout a population of animals. Researchers report today that they have harnessed a so-called gene drive to efficiently endow mosquitoes with genes that should make them immune to the malaria parasite—and unable to spread it. On its own, gene drive won’t get rid of malaria, but if successfully applied in the wild the method could help wipe out the disease, at least in some corners of the world. The approach “can bring us to zero [cases],” says Nora Besansky, a geneticist at the University of Notre Dame in South Bend, Indiana, who specializes in malaria-carrying mosquitoes. “The mosquitos do their own work [and] reach places we can’t afford to go or get to.”

But testing that promise in the field may have to wait until a wider debate over gene drives is resolved. The essence of this long-discussed strategy for spreading a genetic trait, such as disease resistance, is to bias inheritance so that more than the expected half of a subsequent generation inherits it. The gene drive concept attracted new attention earlier this year, when geneticists studying fruit flies adapted a gene editing technology called CRISPR-Cas9 to help spread a mutation—and were startled to find it worked so well that the mutation reached almost all fly progeny. Their report, published this spring in Science (20 March, p. 1300) came out less than a year after an eLife paper discussed the feasibility of a CRISPR-Cas9 gene drive system but warned that it could disrupt ecosystems and wipe out populations of entire species.

A firestorm quickly erupted over the risks of experimenting with gene drives, nevermind applying them in the field. The U.S. National Academy of Sciences (NAS) has convened a committee to weigh the risks and propose safeguards, and the authors of the eLife andScience papers have laid out guidelines for experiments (Science, 28 August, p. 927).